Why did 'God' not go ahead and give fully aquatic mammals, such as whales and dolphins, gills, instead of lungs? It doesn't seem like an intelligent design for such animals.

Oh, and manatees, too? Though they are not cetaceans.

Just to preemptively dispatch a claim I could predict a Theist using of, whales need lungs because lungs are more efficient than gills at that size...consider that that does nothing to explain why dolphins of a smaller size than many types of sharks would not have them. Also, consider the size of modern whale sharks, and prehistoric megalodons.

P.S., It would have also been useful for almost completely and semi aquatic reptiles and mammals like sea and fresh water turtles, marine iguanas, seals, otters, walruses, etc... and penguins could arguably fair will with such aids too.

(20-02-2014 01:32 AM)Raptor Jesus Wrote: P.S., It would have also been useful for almost completely and semi aquatic reptiles and mammals like sea and fresh water turtles, marine iguanas, seals, otters, walruses, etc... and penguins could arguably fair will with such aids too.

Seals, walruses and penguins spend a significant proportion of their day on land. Penguins are birds so they need to actually keep their eggs warm; they incubate the eggs for about 2 months before they hatch. They wouldn't be able to stay out of water for two months if they had gills.

Also, otters beavers wouldn't be able to exert themselves out of water for hours building dams if they had gills instead of lungs.

(20-02-2014 01:32 AM)Raptor Jesus Wrote: P.S., It would have also been useful for almost completely and semi aquatic reptiles and mammals like sea and fresh water turtles, marine iguanas, seals, otters, walruses, etc... and penguins could arguably fair will with such aids too.

Seals, walruses and penguins spend a significant proportion of their day on land. Penguins are birds so they need to actually keep their eggs warm; they incubate the eggs for about 2 months before they hatch. They wouldn't be able to stay out of water for two months if they had gills.

Also, otters also wouldn't be able to exert themselves out of water for hours building dams if they had gills instead of lungs.

But couldn't they all have both? Seems like the best of both worlds if the sky is the limit.

(20-02-2014 01:32 AM)Raptor Jesus Wrote: P.S., It would have also been useful for almost completely and semi aquatic reptiles and mammals like sea and fresh water turtles, marine iguanas, seals, otters, walruses, etc... and penguins could arguably fair will with such aids too.

Seals, walruses and penguins spend a significant proportion of their day on land. Penguins are birds so they need to actually keep their eggs warm; they incubate the eggs for about 2 months before they hatch. They wouldn't be able to stay out of water for two months if they had gills.

Also, otters also wouldn't be able to exert themselves out of water for hours building dams if they had gills instead of lungs.

I put this part as a side note for a reason, for the same reasons you wrote. There are clear reasons why gills would be problematic for their lives. But Arguably If they had gills, they wouldn't need to spend time out of water. And "God" could find other ways to birth babies in water for those penguins, if he is in fact after all "God".

But it could be argued that it would make more sense for "God" to create them with gills, and adaptations for fully aquatic lives (though if "God" made them, they would not be call adaptations). But it could also be argued that they need to be semi aquatic at least.

I care less about this point. It was just a side note. The real point is about the fully aquatic cetaceans .

(20-02-2014 02:02 AM)Chippy Wrote: ...
Also, otters also wouldn't be able to exert themselves out of water for hours building dams if they had gills instead of lungs.

But couldn't they all have both? Seems like the best of both worlds if the sky is the limit.

Yeah, and that's the point. "God" could do whatever he want's, if he is "God", so he could still design them better.

And arguably penguins with some other feature for birthing underwater in the cold Antarctic, or otters given some other life style for survival other than building dams.... wait...what the fuck?! OTTERS DON'T BUILD DAMS!!!

Cute picture though. I don't think anyone would have known how penguins reproduce if it weren't for including that picture. That was helpful...

(20-02-2014 02:12 AM)EvolutionKills Wrote: But couldn't they all have both? Seems like the best of both worlds if the sky is the limit.

Possibly but I think gills are a problem for terrestrial mammals because they are an anatomical vulnerability in relation to mammalian behaviour. Gills represent the external exposure of masses of blood vessels. Male walruses and seals have brutal fights during mating season and they wound themselves all over their upper bodies. They (usually) survive these fights because they have such thick layers of blubber. If they had gill slits that would be an entry point for a tooth and if a tooth entered those it would produce a "bleeder" and death would soon follow. The gills would need muscular lids to close them off and protect them.

Also, I think they would need to have a valve system to direct blood between lungs or gills because if their heart is pumping blood to lungs and gills while they are underwater the lungs will be returning unoxgenated blood back to the heart and the rest of the body and CO2 levels will be rising.

I'd just stick with whales having gills because they have no real terrestrial needs. If they had gills and the rest of their anatomy was the same they would still be able to surface just for the fuck of it and they could stay underwater and avoid Japanese "research".